<?php
abstract class BillMaker {
    protected $storage;

    public function __construct(&$objStorage = null) {
        $this->storage  =   $objStorage;
    }

    public function import($type) {
        $importer   =   $this->create($type);
        $importer->readData();
        $importer->updateBillStorage();
    }

    abstract public function create($type);
}
?>